Common Python Built‑in Functions with Examples

Python provides many built‑in functions that help developers write code more efficiently. Familiarity with these functions can improve programming productivity and make code cleaner and easier to read.

1. len() : Returns the length of a string, list, tuple, etc.

my_list = [1, 2, 3, 4, 5]
print("Length of the list:", len(my_list))

Output: Length of the list: 5

2. sorted() : Returns a new sorted list from an iterable.

my_list = [3, 1, 4, 1, 5, 9]
sorted_list = sorted(my_list)
print("Sorted list:", sorted_list)

Output: Sorted list: [1, 1, 3, 4, 5, 9]

3. sum() : Calculates the sum of a numeric list.

numbers = [1, 2, 3, 4, 5]
total = sum(numbers)
print("Sum of the list:", total)

Output: Sum of the list: 15

4. min() : Returns the smallest item in an iterable.

numbers = [3, 1, 4, 1, 5, 9]
smallest = min(numbers)
print("Minimum value:", smallest)

Output: Minimum value: 1

5. max() : Returns the largest item in an iterable.

numbers = [3, 1, 4, 1, 5, 9]
largest = max(numbers)
print("Maximum value:", largest)

Output: Maximum value: 9

6. abs() : Returns the absolute value of a number.

x = -5
print("Absolute value:", abs(x))

Output: Absolute value: 5

7. round() : Rounds a float to a specified number of decimal places.

x = 3.14159
print("Rounded value:", round(x, 2))

Output: Rounded value: 3.14

8. pow() : Computes the power of a number.

x = 2
y = 3
result = pow(x, y)
print("Power result:", result)

Output: Power result: 8

9. range() : Generates a sequence of integers.

for i in range(5):
    print(i, end=' ')
print()

Output: 0 1 2 3 4

10. enumerate() : Returns an indexed enumeration of an iterable.

fruits = ['apple', 'banana', 'cherry']
for index, fruit in enumerate(fruits):
    print(index, fruit)

Output: 0 apple 1 banana 2 cherry

11. zip() : Aggregates elements from multiple iterables into tuples.

names = ['Alice', 'Bob', 'Charlie']
ages = [25, 30, 35]
zipped = zip(names, ages)
print("Zipped list:", list(zipped))

Output: Zipped list: [('Alice', 25), ('Bob', 30), ('Charlie', 35)]

12. reversed() : Returns an iterator that accesses the given sequence in the reverse order.

my_list = [1, 2, 3, 4, 5]
reversed_list = list(reversed(my_list))
print("Reversed list:", reversed_list)

Output: Reversed list: [5, 4, 3, 2, 1]

13. str() : Converts an object to its string representation.

num = 42
str_num = str(num)
print("String representation:", str_num)

Output: String representation: 42

14. list() : Converts an iterable to a list.

tup = (1, 2, 3)
lst = list(tup)
print("Converted list:", lst)

Output: Converted list: [1, 2, 3]

15. tuple() : Converts an iterable to a tuple.

my_list = [1, 2, 3]
my_tuple = tuple(my_list)
print("Converted tuple:", my_tuple)

Output: Converted tuple: (1, 2, 3)

16. set() : Creates a set of unique elements.

my_list = [1, 2, 2, 3, 4, 4, 5]
unique_elements = set(my_list)
print("Deduplicated set:", unique_elements)

Output: Deduplicated set: {1, 2, 3, 4, 5}

17. dict() : Creates a dictionary from two iterables.

keys = ['a', 'b', 'c']
values = [1, 2, 3]
my_dict = dict(zip(keys, values))
print("Created dictionary:", my_dict)

Output: Created dictionary: {'a': 1, 'b': 2, 'c': 3}

18. all() : Returns True if all elements of the iterable are true.

my_list = [True, True, True]
print("All true?", all(my_list))

Output: All true? True

19. any() : Returns True if any element of the iterable is true.

my_list = [False, False, True]
print("Any true?", any(my_list))

Output: Any true? True

20. bin() : Converts an integer to its binary string representation.

print("Binary of 10:", bin(10))

Output: Binary of 10: 0b1010

21. bool() : Converts a value to a Boolean.

print("1 as bool:", bool(1))
print("0 as bool:", bool(0))

Output: 1 as bool: True 0 as bool: False

22. chr() : Returns the character represented by a Unicode code point.

print("Character for code 65:", chr(65))

Output: Character for code 65: A

23. divmod() : Returns a tuple of (quotient, remainder).

print("Divmod of 10 and 3:", divmod(10, 3))

Output: Divmod of 10 and 3: (3, 1)

24. eval() : Evaluates a string as a Python expression.

expression = "3 + 4"
print("Result of expression:", eval(expression))

Output: Result of expression: 7

25. filter() : Filters elements of an iterable based on a function.

numbers = [1, 2, 3, 4, 5]
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
print("Even numbers:", even_numbers)

Output: Even numbers: [2, 4]

26. float() : Converts a value to a floating‑point number.

print("3 as float:", float(3))

Output: 3 as float: 3.0

27. format() : Formats a string using placeholders.

print("Hello, {name}!".format(name="World"))

Output: Hello, World!

28. input() : Reads a line of input from the user (interactive use).

user_input = input("Please enter your name: ")
print("Hello,", user_input)

Example interaction: Please enter your name: Zhang San Hello, Zhang San

29. int() : Converts a value to an integer.

print("'123' as int:", int("123"))

Output: '123' as int: 123

30. find() : Returns the lowest index of the substring if found, otherwise -1.

text = "Hello, welcome to the world of Python."
index_of_world = text.find("world")
print("Index of 'world':", index_of_world)

Output: Index of 'world': 22

31. map() : Applies a function to all items in an iterable.

numbers = [1, 2, 3, 4, 5]
squared_numbers = list(map(lambda x: x ** 2, numbers))
print("Squared list:", squared_numbers)

Output: Squared list: [1, 4, 9, 16, 25]

32. ord() : Returns the Unicode code point of a character.

print("Unicode of 'A':", ord('A'))

Output: Unicode of 'A': 65

33. slice() : Creates a slice object to specify a range of indices.

my_list = [1, 2, 3, 4, 5]
s = slice(1, 4)
print("Sliced list:", my_list[s])

Output: Sliced list: [2, 3, 4]

34. open() : Opens a file and returns a file object.

with open('example.txt', 'w', encoding='utf-8') as file:
    file.write('Hello, world!')
with open('example.txt', 'r', encoding='utf-8') as file:
    content = file.read()
print("File content:", content)

Output: File content: Hello, world!

35. print() : Prints the given objects to the console.

print("Hello, world!")

Output: Hello, world!

In summary, these common Python built‑in functions cover basic type conversion, arithmetic, string manipulation, file handling, and advanced iteration utilities. Mastering them can greatly boost coding efficiency and readability.